Someone was asking me about helmets, and I can't remember who it was...sorry.
Regardless, I found that
www.soloracer.com has a great selection of entry level and higher helmets, for solo, and track days. They also have Free shipping!
If you are looking to do strictly autocross, there are lots of good Open-Face options, which are very low in cost. However, for track days and trial events, a closed face is much smarter.
I have always run with an open face helmet, even on tracks

and decided recently that I really want a close faced helmet for high speed events. I've been reading up on different options, and I came across the PyroTect
Full Face which is designed and manufactured by Bell (it is derived from their popular RacerIII design), it carries a new SA 2005 rating, and costs less than $250.
With free shipping I couldn' pass it up, so it's on the way. I tried on the Bell Racer III at Summit, to get my sizing correct, but saved $75 by going with the PyroTect. From what I can tell they are very similar.
I also purchased a smoke visor for sunny days.
For entry level Autocross helmets, I've been using a SA2000 G-Force (cheapest brand) and it has done fine for what I need it for. If you're going to run more than a handful of SCCA events next season, I'd suggest trying to get your own helmet.